Reciprocating engine.



7 0 9 1 2 1 nm E F D E T N E T A P 3 S U A M W .6 v 4 4 0- N REGIPROGATING ENGINE.

APPLICATION FILED DBO. 21. 1906.

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WILHELM MAUSS, F BRAKPAN, TRANSVAAL, ASSIGNOR To THE KONOMAX ROCK DRILL SYNDICATE, LIMITED,

RECIPROCATING ENGINE.

Specification of Letters Patent.

OF J OHANN ESBURG, TRANSVAAL.

Patented Feb.- 12, 1907.

Application filed December 21, I906. Serial No. 348.917.

To all whom it may concern.-

Be it known that I, WILHELM MAUSS, mechanical engineer, a German subject, residing at the Rand Central Electric Works, Brakpan,'in the Colony of the Transvaal, have invented certain new and useful Improvements in Controlling the Working Fluid of Rock- -Drilling and other Reciprocating Engines, of

which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to the control of the working fluid for reciprocating engines, such as percussive rock-drilling machines, and

more especially the type of rock-drilling machines describedin the specification of patent application Serial No. 305,685, in which mac ine the rear piston-face is exposed constantly to full pressure While the working fluid (hereinafter referred to as air) operates expansively upon the-relatively larger front piston-face.

. The principal object of the present invention is to provide a simple andefiicient means for effecting the supply, cut-off, and exhaust of. the air for the front cylinder in a machine of the last-named type.

A further object is to provide an admission and exhaust valve for the front cylinder operated by air from either end of the cylinder alternately which shallalways open fully to exhaust,- and so preventcushioning of the piston of the working stroke. v

A further object is to provide a valve mechanism applicable to fluid-operated rock-(hilling and other percussive tools generally, which enables short and light but uncushioned blows to be delivered when desired by simplythrottling the air-supply to the tool and without, as is usual, altering the position of the machine in relation to the body upon which the blows are delivered, which again renders the movement of the valve, and therefore the proper working of the tool, independent of the position of the tool, and which by doing away with possible deadpoints in the valve s movement permits the tool to be started in any position.

These-and other objects are attained by the valve mechanism, of which one form is sh own In the accompanying drawings applied to an expansively-working rock-drilling engine as described in said application, Serial No. 305,685, Figure I being a longitudinal I section of the machine with the piston at its rear limit; and Fig. II a similar view, but showing the piston at the end of its forward travel.

1 0 indicates the cylinder; 1), the larger front piston member working therein; 0, the smaller rear piston member; (1, the piston-rod, to which the drill is chucked; e, the air-inlet, communicating constantly with the'rear pisfrom between the pistons, all of which features are as disclosed in said prior specification, with the exception that a clearance g is smaller piston member.

The valve-gear pro er comprises a doubleheaded piston-valve of known form working within the valve-chest i. r

7' are steps limiting the travel of the piston valve, and leather packing-rings lc preclude rebound of the valve from the stops.

The valve works over the three main ports Z, m, and n. opening directly to atmosphere. m communicates with the front end of the cylinder, and n conducts full-pressure air from the rear cylinder.

0 is a duct taking air from the high-pressure cylinder to the rear of the valve, and p is a similar duct in the front cylinder, leading to the front end of the valve.

The normal -operationi. 6., when using about the ordinary working pressure of air is as follows: The piston and valve being at their extreme backward positions, as in Fig. I, the front of the cylinder is communicating with atmosphere through ports m and Z. Upon opening the air-supply cock-the piston, propelled by face 0, moves freely forward, to deliver its Working blow, and when nearing the end of its outward stroke uncovers hole 0. lBy this means pressure is brought to bear upon the rear end of the valve, the front'face of which is open to exhaust through 1) and The valve being thus thrown forward,'t e position 'of all parts becomes that illustrated in Fig. II. With the valve so disposed, exhaust port Z is closed and I live air is admitted through a and m to the front cylinder, caus- Near the end of such stroke air is admitted to the front of the valve through p and exhausted from behind the same through 0, g,

ton-face, and f the exhaust to atmosphere.

in the present instance turned upon the.

the full pressure upon its rear ing the piston to begin its rearward stroke] Of these Z is the exhaust-port,

' cylinder to tion of its rearward travel is assured.

it ever much thefmaiu pressure on the rear of the valve will be reand f. The valve now returns fully to'its' l 'thr'own back to exhaust, and the drill will initial position, exhaust occurs from the thereupon make a second forward stroke front cylinder, and the cycle recommences iunder full pressure, and so tend to clear As already mentioned; the se uence of Opl itself; and, again, when drilling downward erations just described is effects when mak any difficulty of working due to theFweight ing full strokes with normal air-pressure; of the valve,which might otherwise occur, is but under other conditions, such as when I eliminated by the final throw over of the making light strokes with throttled supply, l-valve under full pressure. It may be ohthe operation is somewhat different. that no material served in this connection In the drawings, g is a smallhole through retardation of the valve would occur when which leakage from the rear ofithe, valvedrilling upwardly, the forward. stroke chest constantly takes place.

since of the valve is in every case made udder full 1' is a small passage leading from the large the front of the valve-chest, its

pressure.

The invention has hitherto been described opening into the large cylinder being so p aced as to be uncovered to pressure by the with reference to the particular type of drill piston when the-latter isrmaking the shortwherein constant pressure is ap ied too.

small rear piston and air is expanr ed against est stroke which is practically desirable. 8, again, is a small passage leading from the a larger front piston and wherein conse quently the valve is called upon to control the port nor other source of high-pressure air to the front end of the valve-chest and opening air in the'iront cylinder only; It is, however, to be understood that the features of thereinto at about the point illustrated.

q, r, and s are all of such bore as to pass air the leakage-hole q and passages r and 8 may advantageously be app ve slowly in comparison with the ducts-o ated piston-controlled valves of percussive p. machines generally e. z;., those or the 'ordi Reduction of working pressure due to throttling will reduce the rearward travel of the nary class in which the c linder is of uniform iston afterclosurc of port a. Such travel, owever, w ll always be sufficient to un bore throughout and full-pressure air is used in either end alternately. Such hole and cover passage 1" to pressure, although in many cases not duct 0 to 'exhahst; In this case passages would be arranged as in the above example to move the valve toexhaust from the front cylinder. The valves would there deadpoints, the. machine would be ran dered capable of working with short and light uncushioned strokes by merely throt tling the air-inlet, and, furthermore, sticking of the drill on the back stroke would to a large extent be overcome. I

I claim as my invention- 1. In a reciprocating engine having a small rear piston area exposed to constant pressure and a relatively larger front piston area against which the air acts expansively, the improved means for controlling the air as hereinbefore described, coinprising'an air-op erate'd valve for controllingadmission to and exhaust from thefrorit c linder', a port for conductinglive'air from t e rear cylinder to the-valve, which port is arranged to be co eved by leakage through q, and-the pres sure in the front cylinder being necessarily higher than atmospheric and being transmitted through 1', the valve will travel suflicientl far to at least partially uncover port Z, an so cause more orv less complete exhaust from the front cylinder. Such exhaustion, however, deprivesthe valve of its normal motive power, and to preclude its moving sluggish y or stopping entirely it is arranged that immediately before uncovering port I the valve shall uncover passage s, thereby admitting in front of itself live air stored in port n, by which a smart comple- It will be understood that the operation of the-valve by functioning of the passages q, r, and 8 tends to occur under all conditions)? working, although the anion tot-aifwhich stroke to cause expansion in the front cylin- "'ered by the small piston upon'its rearward.

lied'to the air' oper by be freed from'tho tendency to hang at I such assages arecapable of passing is relder, air-ducts from the cylinders controlled ative y so small that under normal condiby the piston to operate the valve, asrnall tions of working said by-passes preciably affect the direct working chine as first described.

Besides causing thevalve to operate, howinlet is throttled, the 1", and s assist the efficient operation of t e dr ll in other respects. Thus when full pressure is used, but an accumulation of broken rock in the hole setsup such friction against the drill as to preclude the completion of the full backward stroke after cut oil, the valve will after a short interval be do not apleakage-hole at the rear of the v-alvechest, a of the masmall auxiliaryL pressure-duct from the front cylinder to t e front of the valve-chest adapted to be opened by the (piston alter a certain fraction of its rearwar means for supplying hill-pressure air to 1n sure the final throw-over of the valve to exhaust the front cylinder.

2. In a reciprocating engine having constant full pressure on the rear piston-face and in which the air operatos'expansively on the front piston-face, and having a piston-com passages stroke and a trolled valve for controlling admission to and exhaust from the front cylinder, an air-port from the rear cylinder to the valve for the supply of full-pressure air to the front cylinder which port is adapted to be covered by the rear piston during its backward stroke to produce expansion in the front cylinder.

3. In a reciprocating percussive engine having an air-operated piston-controlled distributing-valve a means for moving the valve to exhaust the front cylinder independ ently of the normal pressure and exhaust ducts for the valve, comprising in combina tion a hole permitting a continuous small leakage from one side of the valve, and a relativelv small pressure-duct to the other side of the valve from the front cylinder adapted to I be opened by the piston at a certain fraction of its backward stroke.

4. In a reciprocating percussive engine having an air-operated piston-controlled disducts for the valve, comprising in combination a hole permitting a continuous small leakagefrom one s1de of the valve, a relatively small pressure-duct to the other side of Y the valve from the front cylinder adapted to be opened by the piston at a certain fraction of its backward stroke, and means for admitting full-pressure air to the latter side of the valve immediately before the valve exhausts the front cylinder. I

5. In a reciprocating percussive engine having an air-operated piston-controlled dis: tributing-valve, fmeans for admitting fullpressure air during the travel of the valve to exhaust the front cylinder, in combinationv with means for exhausting the air at the Opt."

posite endof the valve independently of the 

